The influence of GaPt droplet purification on the catalytic performance of supraparticles as supported catalytically active liquid metal solutions (SCALMS) in propane dehydrogenation

Supported catalytically active liquid metal solutions (SCALMS) are heterogeneous catalysts consisting of metal alloy particles, supported by an inert porous metal oxide matrix. The metal alloy particles consist of catalytically active elements, e.g., Pt, in a low-melting-point metal, such as Ga. At temperatures above 250 °C, these alloys become liquid, allowing active metals to interact at the liquid metal–gas interface, enhancing selectivity and coking resistance in high-temperature dehydrogenation reactions. Current challenges lie, firstly, in the deposition of the metal alloy onto porous supports due to its high surface tension and poor wetting properties. Secondly, the Pt is often not only integrated into the Ga phase but also deposited as Pt nanoparticles onto the entire support material, which is undesired in this context. This study exploits a spray drying-assisted assembly approach yielding supraparticles, enabling a statistical distribution and encapsulation of liquid metal droplets within a porous silica support matrix. Additionally, the Pt is already deposited on Ga droplets in the colloidal state and purified using three different protocols to eliminate unwanted side products before the formation of SCALMS. The different purification methods directly decrease the deactivation rate of GaPt/SiO₂ SCALMS supraparticles from 0.024 to 0.019 h⁻¹ in propane dehydrogenation.